Hurricane mitigation by combined seeding with condensation and freezing nuclei

Abstract

The invention provides method for treating a tropical cyclone, a tropical storm or a tropical depression. The method includes reducing unloading of cloud parcel water in the tropical cyclone, tropical storm or tropical depression. In a preferred embodiment, unloading of cloud parcel water is accomplished by seeding with cloud condensation nuclei, such as sub-micron ammonium sulfate particles. The treatment is preferably applied to the lower parts of peripheral clouds in the tropical cyclone, tropical storm or tropical depression below the 0 C isotherm level.

Description

FIELD OF THE INVENTION[0001]This invention relates to methods for reducing the intensity of a hurricaneBACKGROUND OF THE INVENTION[0002]The devastating United States hurricane season of 2005 renewed interest in developing methods to mitigate the strong winds of hurricanes. Since a hurricane's destructive potential increases with the cube of its strongest winds, a reduction as small as 10% in its wind speed would be beneficial. Hurricane modification involves intervening in the energy pathways in the moist tropical convective clouds that energize the hurricane. The energy pathways in a hurricane are depicted in FIG. 1. These energy pathways take heat from the sea surface mainly by evaporation (A). This latent heat is observed as vapor condensation into cloud drops (B). Some of this heat is reclaimed if the drops re-evaporate (C), but the heat remains in the air if the drops precipitate as rain (D). Drops that ascend into the sub-zero portion of the cloud freeze, and release additiona...

AI Technical Summary

Problems solved by technology

The lack of response on the other days was interpreted to be the result of faulty execution of the seeding or of poorly selected subject hurricanes.

However, in the mid-1980s it became clear from observations in unmodified hurricanes that hurricanes contain insufficient super-cooled water available for freezing in the clouds due to premature rainout for the seeding to be effective.

It was then suggested that the positive results of the seeding experiments in the 1960s stemmed from an inability to distinguish between the results of human intervention and the natural behavior of hurricanes.

When the ambient lapse rate of the temperature cools with height faster than the cloud parcel, the cloud will become warmer than the ambient air as it rises, and the atmosphere is said to be unstable.

When the opposite occurs the atmosphere is stable and provides no support for development of convective clouds.

This means that tropical maritime clouds did lose their condensate loading while growing they would not be able to develop in the typical atmosphere, which is the atmosphere that supports the development of hurricanes.

Therefore, tropical maritime clouds, including those in hurricanes, lose their water while growing.

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